1. Field of the Invention
The subject invention relates to a method for displaying time. More specifically, the subject invention relates to a method for displaying time at a particular coordinate position on the earth.
2. Description of the Prior Art
It is often desirable to know the commencement of light, darkness and the twilight. This need is often complicated when travelling between time zones. Prior clock systems provide clocks that indicate times for sunrise, sunset and twilight. One such clock system is described in the U.S. Pat. No. 4,669,891 to the inventor herein, Rosevear. The prior Rosevear '891 patent discloses a keyboard for inputting an area code or an airport designation for a geographical location. A memory contains information of the sunrise, the sunset time and the twilight duration for each area code or airport designation that can be selected. A microprocessor generates a signal, based on information gathered from the memory, which corresponds to either the input area code or the input airport designation. The signal is then presented on a video display screen in parallel vertical sections that represent juxtaposed hours of the day for the selected geographical location that includes each of the day, night and twilight hours.
Another clock system is described in the U.S. Pat. No. 6,449,219 to Hepp et al. (the '219 patent). The '219 patent provides an analog clock that is contained within a time sensing information display device. The display device contains a rectangular display area. On the display area is a graphical depiction of a tree with a round treetop, a horizon and a sky. The analog clock is incorporated within the round treetop. As the time of day changes, the sky alters to show a sun or a moon that is either waxing or waning. Furthermore, the display device incorporates a global positioning receiver which allows the proper display of the time, the sun and the moon based on the display devices' geographical location.
Although the prior art clock systems provide a visual display of day, night and twilight hours or a visual display of the sun and moon based on a geographical location, derived from a global positioning system, there remains an opportunity for a visual clock system which provides a more instantly understandable method of displaying the day, night and twilight hours based on geographical coordinates and a calendar date.